Peel-treating agent and method for producing the peel-treating agent

ABSTRACT

A peel-treating agent comprising a reaction product of an aliphatic isocyanate having an aliphatic group of at least 8 carbon number with an ethylene/vinyl alcohol copolymer or polyvinyl alcohol as an effective component, wherein a bisurea form content in the reaction product is at most 3 wt %.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a peel-treating agent comprisinga reaction product of an aliphatic isocyanate having an aliphatic groupof at least 8 carbon number with an ethylene/vinyl alcohol copolymer orpolyvinyl alcohol as an effective component, and a method for producingthe peel-treating agent.

[0003] 2. Description of Background Art

[0004] Heretofore, there was known a urethane type peel-treating agenthaving an alkyl isocyanate added to an ethylene/vinyl alcohol copolymeror polyvinyl alcohol. For example, JP-B-2-7988 discloses a urethane typepeel-treating agent of polyvinyl alcohol. JP-B-60-30355 discloses aurethane type peel-treating agent of ethylene/vinyl alcohol copolymer.Also, JP-B-4-28002 discloses a method for producing the urethane typepeel-treating agent of ethylene/vinyl alcohol copolymer, whereinreaction including its intermediate product is carried out in a solutionstate by using a water-soluble solvent from the initiation to the end ofthe reaction.

[0005] Generally, in the production of the above peel-treating agent, anethylene/vinyl alcohol copolymer or polyvinyl alcohol as a startingmaterial is dispersed in an organic solvent such as toluene, and awater-soluble solvent such as dimethyl sulfoxide is added thereto withheating, and an aliphatic isocyanate such as octadecyl isocyanate isadded and reacted with the ethylene/vinyl alcohol copolymer or polyvinylalcohol. The ethylene/vinyl alcohol copolymer or polyvinyl alcohol isgradually dissolved when a water-soluble solvent such as dimethylsulfoxide is added, and the periphery of a powder of the ethylene/vinylalcohol copolymer or the like is reacted with an isocyanate to produce aurethane product of the aliphatic isocyanate with the ethylene/vinylalcohol copolymer or polyvinyl alcohol (hereinafter referred to as“urethane product”). Since the urethane product is dissolved in toluene,the reaction proceeds in a solution state. In this case, in addition toan aimed urethane product, a bisurea form is by-produced and isprecipitated in a reaction solution or is contained in the reactionsolution, and is finally contained in the aimed urethane product. Thebisurea form thus by-produced is a compound having a bond of —NHCO—NH—in the center chained with an alkyl group of an aliphatic group at theboth terminals of a molecule obtained by reaction of water and analiphatic isocyanate used.

[0006] If the bisurea form is precipitated in the reaction solution, itdamages a transportation pump when transporting the reaction solutionfrom a reactor, and traps dusts to cause occlusion or clogging of a net(strainer), thereby lowering a productivity.

[0007] Also, if the bisurea form is contained in an aimed urethaneproduct, the bisurea form is transferred to an adhesive agent layer tolower its adhesive force when a peel-treating agent containing thebisurea form is coated on the back side of a tape opposed to theadhesive agent.

[0008] Further, in order to obtain an aimed peel strength, an additionrate of an aliphatic isocyanate to an ethylene/vinyl alcohol copolymeror polyvinyl alcohol as starting materials is adjusted, but theisocyanate is consumed in the production of the bisurea form and apeel-treating agent having the aimed peel strength is hardly obtained.Still further, a peel-treating agent is usually supplied to a tape makerin a powdery state, but a tape maker having no facility of dissolving apeel-treating agent buys the peel-treating agent as a 10% solution andtransports the solution and stores in a storing tank at normaltemperature (around 25° C.). During storing at normal temperature, abisurea form is precipitated if a temperature in the storing tank islowered only a little by environmental temperature difference, andtroubles are caused when storing or measuring an amount to betransported into a reaction tank.

SUMMARY OF THE INVENTION

[0009] The present invention relates to a peel-treating agentcharacterized in that a bisurea form content in an urethane product isat most 3 wt %, and a method for producing the peel-treating agent.Thus, by adjusting a bisurea form in a urethane product to not more than3 wt %, there is provided an adhesive tape which prevents deteriorationof performances of an adhesive agent caused by transferring of thebisurea form from a peel-treating layer to an adhesive layer, and thereis also provided a peel-treating agent which can be stored ortransported stably at normal temperature in a 10% toluene solution.Also, the method for producing a peel-treating agent in accordance withthe present invention is a production method which produces apeel-treating agent having a stable quality at an improved yield.

[0010] That is, the present invention provides a peel-treating agentcomprising a reaction product of an aliphatic isocyanate having analiphatic group of at least 8 carbon number with an ethylene/vinylalcohol copolymer or polyvinyl alcohol as an effective component,wherein a bisurea form content in the reaction product is at most 3 wt%.

[0011] Also, the present invention provides a method for producing apeel-treating agent comprising a reaction product of an aliphaticisocyanate having an aliphatic group of at least 8 carbon number with anethylene/vinyl alcohol copolymer or polyvinyl alcohol as an effectivecomponent, which comprises adjusting a particle size of theethylene/vinyl alcohol copolymer or polyvinyl alcohol to at most 10mesh, subjecting to a dehydration operation to reduce their watercontent and then reacting with an aliphatic isocyanate, therebycontrolling a bisurea form content in a reaction product to at most 3 wt%.

[0012] Further, the present invention provides a method for producing apeel-treating agent comprising a reaction product of an aliphaticisocyanate having an aliphatic group of at least 8 carbon number with anethylene/vinyl alcohol copolymer or polyvinyl alcohol as an effectivecomponent, which comprises adjusting a particle size of theethylene/vinyl alcohol copolymer or polyvinyl alcohol to at most 10mesh, subjecting to azeotropic dehydration to reduce their watercontent, and then reacting with an aliphatic isocyanate, therebycontrolling a bisurea form content in the reaction product to at most 3wt %.

[0013] Still further, the present invention provides a method forproducing a peel-treating agent comprising a reaction product of analiphatic isocyanate having an aliphatic group of at least 8 carbonnumber with an ethylene/vinyl alcohol copolymer or polyvinyl alcohol asan effective component, which comprises adjusting a particle size of theethylene/vinyl alcohol copolymer or polyvinyl alcohol to at most 10mesh, subjecting to dehydration operation (preferably azeotropicdehydration) to reduce their water content, and removing a minor amountof a bisurea form by trapping with a sealed type pressure-filtratingmachine to control the bisurea content in the reaction product to atmost 3 wt %.

[0014] Still further, the present invention provides a method forproducing a peel-treating agent comprising a reaction product of analiphatic isocyanate having an aliphatic group of at least 8 carbonnumber with an ethylene/vinyl alcohol copolymer or polyvinyl alcohol asan effective component, which comprises adjusting a particle size of theethylene/vinyl alcohol copolymer or polyvinyl alcohol to at most 10mesh, subjecting to a dehydration operation (preferably azeotropicdehydration) to reduce their water content, and removing a minor amountof this urea form by trapping with a leaf-like sealed typepressure-filtrating machine to control the bisurea form content in thereaction product to at most 3 wt %.

[0015] Also, the present invention provides an adhesive tape or sheetcomprising a substrate, an adhesive urea and a peel-treating agentlayer, wherein a bisurea form content in a reaction product in thepeel-treating agent layer is at most 3 wt %.

[0016] Also, the present invention provides a release sheet comprising asubstrate and a peel-treating agent layer, wherein a bisurea formcontent in a reaction product in the peel-treating agent layer is atmost 3 wt %.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] A peel-treating agent of the present invention, wherein a bisureaform content in a urethane product is at most 3 wt %, can be produced inthe following manner. A particle-like ethylene/vinyl alcohol copolymeror polyvinyl alcohol having a particle size of at most 10 mesh isdispersed in a non-polar solvent such as toluene, and is subjected toazeotropic dehydration, and after lowering a temperature, awater-soluble solvent such as dimethylsulfoxide is optionally addedthereto, and an aliphatic isocyanate such as octadecyl isocyanate isdropwise added thereto to make reaction.

[0018] After adjusting a particle size of the ethylene/vinyl alcoholcopolymer or polyvinyl alcohol to at most 10 mesh, a method for removinga water content is not specially limited but may be carried out by adryer. It is industrially preferable to employ an azeotropic dehydrationmethod as a method for removing a water content, and the azeotropicdehydration operation includes a method for separating and removing awater content on the half way of a refluxing apparatus while refluxing.Also, a solvent used is not specially limited as far as it can beazeotropic with water, but it is preferable to employ the same solventusable for coating the peel-treating agent of the present invention on asubstrate, and preferable examples include toluene and xylene.

[0019] The finishing or end point of reaction can be confirmed bymeasuring a remaining amount of an isocyanate compound in a reactionmixture by an infrared spectrophotometer. Also, when finishing the abovereaction, a catalyst such as an organic tin compound to accelerate areaction between a hydroxyl group and an isocyanate group may beoptionally used. After finishing the reaction, water is added toseparate an oil layer and a water layer, and the oil layer is preferablyfiltrated through a filter to trap a minor amount of a bisurea form. Thefilter usable is not specially limited, but a sealed typepressure-filtrating machine is preferable since an object is to take afiltrate containing a reaction product and a solvent used is an organicsolvent such as toluene. Commercially available examples of the sealedtype pressure-filtrating machine include products such as tradename:Fundaback Filter or tradename: Leaf Filter, manufactured byIshikawajima-Harima Heavy Industries Co., Ltd., and examples of a sealedtype leaf-like pressure-filtrating machine include the above tradename:Leaf Filter and tradename: Ultrafilter manufactured by Miura ChemicalEquipment Co., Ltd. Either a system of receiving a solution by anotherreceiver through a filter from a container containing the solution or acirculating system of recirculating a solution from a containercontaining the solution through a filter into the container containingthe solution may be used.

[0020] The oil layer (toluene, peel-treating agent) is introduced into acontainer previously containing methanol, and a reaction product isfiltrated and dried to obtain a peel-treating agent as an aimed urethaneproduct.

[0021] A ratio of an aliphatic isocyanate having an aliphatic group ofat least 8 carbon number to an ethylene/vinyl alcohol copolymer orpolyvinyl alcohol is not specially limited, but the aliphatic isocyanateis generally from 0.5 to 1.5 equivalent, preferably from 0.6 to 1.1equivalent, to a hydroxyl group of the ethylene/vinyl alcohol copolymeror polyvinyl alcohol.

[0022] A particle size of the ethylene/vinyl alcohol copolymer orpolyvinyl alcohol used in the production method of the present inventionis preferably smaller than 10 mesh, more preferably smaller than 20mesh.

[0023] The ethylene/vinyl alcohol copolymer usable in the presentinvention has a polymerization degree of from 500 to 3,000, preferablyfrom 800 to 2,500, and an ethylene content of from 5 to 90 mol %,preferably from 20 to 60 mol %. Examples of commercially availableproducts include tradename Eval manufactured by Kuraray Co., Ltd.: gradeEP-F101, EP-H101, EP-E105 and EP-G110, and SOARNOL, manufactured byNippon Synthetic Chemical Industry Co., Ltd.: grade ZL, Z, ZT, E and ET.Also, it is possible to use an ethylene/vinyl alcohol copolymer havingethylene oxide added, which is synthesized by addition-polymerizeethylene oxide into a vinyl group of an ethylene/vinyl alcoholcopolymer. Its commercially available examples include tradenameSUMIGUARD grade 300K or tradename SUMIGUARD grade 300G manufactured bySumitomo Chemical Co., Ltd.

[0024] A polyvinyl alcohol used in the present invention has apolymerization degree of from 100 to 3,000, preferably from 150 to 2,000and a saponification degree of from 50 to 100%, preferably from 60 to100%. Its commercially available examples include tradename GOHSENOL Ntype POVAL (NH-26, NH-20, NH-18, N-300, NH-14, NH-11, NL-05), A typePOVAL (AH-26, AH-22, AH-17, A-300, C-500, P-610, AL-06), G type POVAL(GH-23, GH-20, GH-17, GM-14, GM-14L, GL-05, GL-03), and K type POVAL(KH-20, KH-17, KM-11, KL-05, KL-03, KP-08, KP-06, NK-05) manufactured byNippon Synthetic Chemical Industry Co., Ltd.

[0025] An aliphatic group of an aliphatic isocyanate use in the presentinvention is not specially limited, examples of which include an alkylgroup, an alkenyl group, an alkynyl group and the like, preferably analkyl group. The aliphatic group may be branched chain-like, but alinear chain-like aliphatic group is more preferable.

[0026] The aliphatic group should have a carbon number of at least 8 andthere is no special upper limit, but the carbon number is preferably atmost 30, more preferably at most 20.

[0027] Examples of the aliphatic isocyanate include a monoalkylisocyanate such as octyl isocyanate or dodecyl isocyanate (laurylisocyanate), preferably octadecyl isocyanate (stearyl isocyanate).Generally, octadecyl isocyanate includes monoalkyl isocyanatesrespectively having alkyl groups of a carbon number of 12, a carbonnumber of 14, a carbon number of 16, a carbon number of 17, a carbonnumber of 18 and a carbon number of 20, and its content ratio includes 1to 10 wt % of an isocyanate having an alkyl group of a carbon number of16, 0.5 to 4 wt % of an isocyanate having an alkyl group of a carbonnumber of 17 and 80 to 98 wt % of an isocyanate having an alkyl group ofa carbon number of 18, which is a commercially available mixture. Apreferable commercially available mixture includes 8 to 9 wt % of anisocyanate having an alkyl group of a carbon number of 16, 3 to 4 wt %of an isocyanate having an alkyl group of a carbon number of 17 and 85to 87 wt % of an isocyanate having a carbon number of 18 as maincomponents, and this mixture is commercially available as a tradename:MILLIONATE 0 manufactured by Hodogaya Chemical Co., Ltd.

[0028] These isocyanates may be used respectively alone or in acombination of two or more.

[0029] Examples of a substrate used for an adhesive tape or a releasesheet of the present invention include a film of nylon, polyvinylchloride, polyolefin such as polyethylene, polypropylene or polyester,and the like, and a paper of fibrous material such as woodfree paper,craft paper or crepe paper, but the substrate is not limited to theseexamples.

[0030] The substrate film may be stretched or nonstretched, but astretched film is preferably in view of its strength, examples of whichinclude a stretched polypropylene film, a stretched polyester film andthe like. Its stretch ratio is not specially limited.

[0031] The substrate generally has a thickness of from 10 to 500 μm,preferably from 30 to 200 μm.

[0032] In case of an adhesive tape, a peel-treating layer is formed onthe opposite side of an adhesive layer of the substrate. Thepeel-treating layer is provided in such a manner as to enable eachrewinding of an adhesive tape winding.

[0033] A method for coating a peel-treating agent on the substrate maybe any of known conventional methods. For example, a peel-treating agentsolution having the peel-treating agent dissolved in a solvent such astoluene may be coated by a coating machine such as a gravure coater, anair knife coater or the like.

[0034] The peel-treating layer has a thickness of from 0.1 to 4 μm,preferably from 0.2 to 1 μm.

[0035] Also, in order to prevent static electricity or to preventgelation, the peel-treating agent may contain a water-soluble solventsuch as dimethyl sulfoxide, N,N-dimethylformamide orN-methylpyrrolidone, or the water-soluble solvent may be contained in apeel-treating agent solution having the peel-treating agent of thepresent invention dissolved in toluene or xylene.

[0036] An adhesive layer is formed on one side of a substrate of anadhesive tape, an adhesive sheet or a release sheet. The adhesive layercomprises an adhesive agent as the main component. The adhesive agentused in the present invention is not specially limited, and examplesinclude a rubber type adhesive and an acrylic adhesive.

[0037] The rubber type adhesive may be any of natural rubber type andsynthetic rubber type adhesives, and examples of the synthetic rubbertype adhesive include a styrene/isobutylene/styrene copolymer and astyrene/butadiene/styrene copolymer.

[0038] Examples of the acrylic adhesive include an alkyl ester typepolymer of acrylic acid or methacrylic acid, or an adhesive comprisingan acrylic polymer having an average molecular weight of 5,000 to3,000,0000 as the main component which comprises 50 to 99.5 wt % of analkyl ester of acrylic acid or methacrylic acid and 0.5 to 50 wt % of anunsaturated monomer copolymerizable therewith.

[0039] If necessary, the adhesive layer may further contain a tackifiersuch as a petroleum type resin, a terpene type resin, a rosin type resinor a coumarone type resin, a plasticizer, an antioxidant, a coloringagent and the like.

[0040] A method for coating an adhesive on a substrate is carried outfor example by a method which comprises dissolving the adhesive agent ina solvent such as toluene. and coating the adhesive agent solution by aroll coater, a gravure coater, an air knife or the like. The adhesivelayer usually has a thickness of 1 to 100 μm, preferably 20 to 80 μm.

EXAMPLES

[0041] Hereinafter, the present invention is further illustrated withreference to Examples. (All of parts are parts by weight.)

Example 1

[0042] (Preparation Method of Peel-Treating Agent)

[0043] Particles of an ethylene/vinyl alcohol copolymer (tradename EVAL,grade F101, manufactured by Kuraray Co., Ltd.) are sieved by a 100 meshsieve, and 100 parts of the sieved ethylene/vinyl alcohol copolymerhaving a particle size less than 10 mesh is dispersed in 2,000 parts oftoluene, and the resultant dispersion was refluxed in a refluxingapparatus for 2 hours, during which a water content was separated andremoved, and the resultant product was cooled to 40° C., and 730 partsof dimethyl sulfoxide was added thereto, and 562 parts of octadecylisocyanate (tradename: MILLIONATE 0, manufactured by Hodogaya ChemicalCo., Ltd.) was dropwise added thereto, and the resultant mixture wasreacted at 120° C. for 4 hours. During the reaction, a remainingisocyanate group in the reaction system was measured by an infraredspectrometer, and the reaction was decided to reach the end when theremaining isocyanate group disappeared. After the reaction, 335 parts ofwater was added to the reaction mixture, and the reaction solution wasseparated, and 4,130 parts of the reaction solution of toluene layer wasplaced in methanol to precipitate a white precipitate, and theprecipitate was filtrated and washed with methanol, and was dried andpulverized to obtain 636 parts of the aimed urethane product.

[0044] A bisurea form of the aimed urethane product thus obtained wasanalyzed by GPC (gel permeation chromatography), but the bisurea formwas not detected.

[0045] (Analytical Conditions of GPC)

[0046] GPC: HLC-8020, manufactured by TOSOH CORPORATION, solvent:tetrahydrofuran, flow rate: 1 ml/min, column: G6000, G-4000, G-2500,three columns in total.

Comparative Example 1

[0047] 100 Parts of an ethylene/vinyl alcohol copolymer (tradename EVAL,grade F101, manufactured by Kuraray Co., Ltd.) was dispersed in 2,000parts of toluene, and the resultant dispersion was refluxed for 2 hoursin a refluxing apparatus, during which a water content was separated andremoved, and the resultant product was cooled to 40° C., and 730 partsof dimethyl sulfoxide was added thereto, and 562 parts of octadecylisocyanate (tradename: MILLIONATE O, manufactured by Hodogaya ChemicalCo., Ltd.) was dropwise added thereto with stirring, and the resultantmixture was reacted at 120° C. for 4 hours. During the reaction, aremaining isocyanate group in the reaction system was measured, and thereaction was decided to reach the end when the remaining isocyanategroup disappeared.

[0048] After the reaction, 335 parts of water was added to the reactionmixture, and the resultant reaction solution was separated, and thereaction solution of toluene layer was poured into 4,130 parts ofmethanol to precipitate a white precipitate. The precipitate thusobtained was filtrated and washed with methanol, and was dried andpulverized to obtain 636 parts of an aimed urethane product.

[0049] A bisurea form in the urethane product thus obtained was analyzedby GPC under the same conditions as in Example 1, and as this result, 4wt % of a bisurea form was detected.

[0050] (Storing Test)

[0051] Each of the urethane products obtained in Example 1 andComparative Example 1 was dissolved in toluene so as to make a 10 wt %solution, and the solution was stirred for 30 minutes and was allowed tostand at normal temperature (25° C.) for 1 day and was visually checkedas to whether a precipitate was produced or not. There was noprecipitate in the toluene solution having the product of Example 1dissolved, but there was a precipitate in the toluene solution havingthe product of Comparative Example 1 dissolved.

[0052] The urethane product obtained in Example 1 was dissolved intoluene to prepare a 1 wt % solution, and the solution was coated on acorona discharge-treated side (one side) of a polypropylene film(hereinafter referred to as “OPP”) as a substrate by a bar coater. Acoated amount of the peel-treating agent was adjusted so as to provide16 g/m² in terms of solid content calculation. The coated product wasthen dried at 90° C. for 1 minute to obtain a release sheet.

[0053] The adhesive surface of a pressure-sensitive adhesive (polyestertape 31E, manufactured by Nitto Denko Corporation) was placed in anopposed state to the peeltreating agent-coated surface of the releasesheet, and the two layers were pressed and bonded by a roller having aself weight of 2 kg to prepare a plurality of test pieces having a widthof 25 mm. The test pieces were subjected to a test in accordance withJIS Z0237 (test method of adhesive tape or adhesive sheet) in thefollowing manner.

[0054] Each of the test pieces was allowed to stand (store) at aconstant temperature of 20° C. under a constant humidity of a relativehumidity of 65% for 1 day.

[0055] Thereafter, an initial peeling force (gf/25 mm) and an initialremaining adhesive force (gf/25 mm) of the test piece were measured at aconstant temperature of 20° C. under a constant relative humidity of65%. The peeling force was measured by peeling the release sheet fromthe pressure-sensitive adhesive under a condition of 90° peeling at apeeling rate of 300 mm/min. The remaining adhesive force was measured bypressing the adhesive face of the pressure-sensitive adhesive (thepeeling force of which was measured as mentioned above) onto astainless-made panel by a roller having a self weight of 2 kg and thenpeeling the pressure-sensitive adhesive from the panel under a conditionof 180° peeling at a peeling rate of 300 mm/min. As this result, thepeeling force was 2.7 N/25 mm and the remaining adhesive force was 6.5N/25 mm. Thus, these results proved that the peel-treating agent of thepresent invention had satisfactory performances.

[0056] As evident from Example 1, the production method of Example 1using an ethylene/vinyl alcohol copolymer having a particle size smallerthan 10 mesh produces a less amount or substantially no amount of abisurea form as compared with the production method of ComparativeExample 1, and consequently the peel-treating agent of Example 1 isproduced at a higher yield, and since an isocyanate is not consumed inthe formation of the bisurea form, an addition rate of an aliphaticisocyanate into an ethylene/vinyl alcohol copolymer or polyvinyl alcoholis constant, thereby easily producing an aimed peel-treating agent.Also, even when the 10% toluene solution is stored at normaltemperature, a bisurea form does not precipitate and consequently thetoluene solution can be easily transported and stored.

[0057] As evident from Example 1, the peel-treating agent of the presentinvention has a satisfactory peeling force and does not produce asubstantial amount of bisurea form, and consequently, when the adhesivetape prepared in Example 1 is stored for a long term, there is no fearthat a bisurea form, which is a lower molecular weight material ascompared with the peel-treating agent transfers into the adhesive agentlayer and the adhesive force is lowered.

[0058] The entire disclosure of Japanese Patent Application No.2001-211895 filed on Jul. 12, 2001 including a specification, claims anda summary are incorporated herein by reference in its entirety.

What is claimed is:
 1. A peel-treating agent comprising a reactionproduct of an aliphatic isocyanate having an aliphatic group of at least8 carbon number with an ethylene/vinyl alcohol copolymer or polyvinylalcohol as an effective component, wherein a bisurea form content in thereaction product is at most 3 wt %.
 2. A method for producing apeel-treating agent comprising a reaction product of an aliphaticisocyanate having an aliphatic group of at least 8 carbon number with anethylene/vinyl alcohol copolymer or polyvinyl alcohol as an effectivecomponent, which comprises adjusting a particle size of theethylene/vinyl alcohol copolymer or polyvinyl alcohol to at most 10mesh, subjecting to a dehydration operation to reduce their watercontent and then reacting the adjusted ethylene/vinyl alcohol copolymeror polyvinyl alcohol with the aliphatic isocyanate.
 3. A method forproducing a peel-treating agent comprising a reaction product of analiphatic isocyanate having an aliphatic group of at least 8 carbonnumber with an ethylene/vinyl alcohol copolymer or polyvinyl alcohol asan effective component, which comprises adjusting a particle size of theethylene/vinyl alcohol copolymer or polyvinyl alcohol to at most 10mesh, subjecting to azeotropic dehydration operation to reduce theirwater content and then reacting the adjusted ethylene/vinyl alcoholcopolymer or polyvinyl alcohol with the aliphatic isocyanate.
 4. Themethod for producing a peel-treating agent according to claim 2, whereinthe reaction product of an aliphatic isocyanate having an aliphaticgroup of at least 8 carbon number with an ethylene/vinyl alcoholcopolymer or polyvinyl alcohol is purified by means of a sealed typepressure-filtrating machine.
 5. The method for producing a peel-treatingagent according to claim 3, wherein the reaction product of an aliphaticisocyanate having an aliphatic group of at least 8 carbon number with anethylene/vinyl alcohol copolymer or polyvinyl alcohol is purified by asealed type pressure-filtrating machine.
 6. The method for producing apeel-treating agent according to claim 2, wherein the reaction productof an aliphatic isocyanate having an aliphatic group of at least 8carbon number with an ethylene/vinyl alcohol copolymer or polyvinylalcohol is purified by means of a leaf-like sealed typepressure-filtrating machine.
 7. The method for producing a peel-treatingagent according to claim 3, wherein the reaction product of an aliphaticisocyanate having an aliphatic group of at least 8 carbon number with anethylene/vinyl alcohol copolymer or polyvinyl alcohol is purified bymeans of a leaf-like sealed type pressure-filtrating machine.
 8. Anadhesive tape or sheet comprising a substrate, an adhesive layer and apeel-treating layer, wherein the peel-treating layer contains apeel-treating agent as defined in claim
 1. 9. A release sheet comprisinga substrate and a peel-treating layer, wherein the peel-treating layercontains a peel-treating agent as defined in claim 1.